Vehicles are provided with seat restraints systems such as seat belts in order to restrain occupants in the seat. The proper engagement and operation of the seat belt ensures the safety of a driver and his or her occupants.
Seat belts often incorporate sensors that provide data to other vehicle restraint vehicle systems such as airbags. Deployment of an airbag may partially depend on the information supplied by the sensor in the seat belt, such as a sensor may determine the weight of an object in the seat.
A tension sensor with the ability of sensing the tension in the belt system can be used to more accurately differentiate the size of the vehicle occupant. Additionally, a tension sensor can also be used to indicate that the seat belt is properly tightened and properly engaged or latched.
International Publication No. WO 02/06092 A1 discloses a seat belt tension sensor assembly, which includes a housing, a pair of magnets, and a Hall effect device all arranged to be coupled to an “anchor side” of a seat belt system (not the “buckle” side). The arrangement of the magnets relative to the sensor is not as integrated into the overall seat belt assembly as desired. In addition, the pair of magnets are oriented face to face wherein the direction of magnetization is in the same axis for both magnets, not in an opposite orientation. It is believed that this arrangement limits the useful tension resolving capabilities of the device.
Moreover, prior art latch detection systems that indicate positive seat belt buckle engagement consists of a mechanical switch subject to wear by mechanical contact of the switch pieces, thus representing a potential failure for indicating positive engagement of the seat belt buckle assembly.
Accordingly, there is a need for a seat belt tension sensor assembly that minimizes or eliminates one or more of the problems set forth above.